- Tumor size will be calculated using the sum of the largest cross-sectional perpendicular diameters of contrast-enhancing tumor for high-grade tumors, the sum of the largest cross-sectional perpendicular diameters of FLAIR abnormality for low-grade tumors, or as worsened spectroscopic characteristics for any tumor type (development of ≥ 2 new voxels with CNI ≥ 3, or ≥ 25% increase in the sum of the CNI ratios within a group of previously abnormal voxels [where abnormal is defined as CNI ≥ 3]).